Organic electroluminescence display device

ABSTRACT

An organic electroluminescence display device is provided. The organic electroluminescence display device includes plural organic electroluminescence elements. Each organic electroluminescence element includes: a lower electrode; an insulating layer having an opening, in which a lower electrode is exposed at the bottom of the opening; an auxiliary wiring; a stacked structure provided from a portion over the lower electrode exposed at the bottom of the opening to a portion of the insulating layer surrounding the opening, including a light emitting layer made of an organic light-emitting material; and an upper electrode. At least one layer of the stacked structure partially contacts the auxiliary wiring. The insulating layer and the auxiliary wiring are provided in common to the plurality of organic EL elements. The upper electrode covers the whole surface of the stacked structures and the auxiliary wiring.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.12/114,606 filed May 2, 2008, which claims priority to Japanese PatentApplication JP 2007-127805 filed on May 14, 2007 and Japanese PatentApplication JP 2008-037190 filed on Feb. 19, 2008, respectively, theentire contents of which are being incorporated herein by reference.

BACKGROUND

The present disclosure relates to an organic electroluminescence displaydevice.

In an organic electroluminescence element (abbreviated to an organic ELelement) forming an organic electroluminescence display device(abbreviated to an organic EL display device) which useselectroluminescence (hereinafter, abbreviated to EL) as an organicmaterial, a stacked structure formed by stacking an organic holetransport layer, an organic light-emitting layer and the like isprovided between a lower electrode and an upper electrode, on whichattention is focused as a light-emitting element capable of emittinglight at high luminance by low-voltage DC driving.

Since the above organic EL element has a response speed of 1 microsecondor less, duty driving by a passive matrix system is possible in theorganic EL display device. However, when the duty ratio becomes higherwith the increase of the number of pixels, it is necessary to supplylarge electric current instantaneously to the organic EL element inorder to secure sufficient luminance, which tends to cause damage to theorganic the organic EL element.

On the other hand, in an active matrix drive system, signal voltage isheld by forming a storage capacitor as well as a thin-film transistor(hereinafter, abbreviated to TFT) at each sub-pixel. Therefore, it ispossible to constantly supply drive current according to the signalvoltage to the organic EL element during a desired period in one displayframe. Accordingly, it is not necessary to supply instantaneously largecurrent to the organic EL element such as in the passive matrix system,which reduces damage to the organic EL element. Note that one pixelusually includes three kinds of sub pixels which are a redlight-emitting sub pixel emitting red color, a green light-emitting subpixel emitting green color and a blue light-emitting sub pixel emittingblue color.

In the above organic EL display device of the active matrix drivesystem, as showing schematic partial cross-sectional view in FIG. 13 andshowing schematic partial plan view in FIG. 14, a TFT is provided on afirst substrate 11 so as to correspond to each sub pixel, and these TFTsare covered by an interlayer insulating layer 16 (a lower interlayerinsulating layer 16A and an upper interlayer insulating layer 16B). Alower electrode 121 which is electrically connected to the TFT isprovided on the upper layer interlayer insulating layer 16B by each subpixel. An insulating layer 124 is further formed on the upper interlayerinsulating layer 16B including the lower electrode 121, and an opening126 in which the lower electrode is exposed at the bottom thereof isprovided in the insulating layer 124. A stacked structure 123 isprovided at a portion from a portion over the lower electrode 121exposed at the bottom of the opening 126 to a portion 124′ of theinsulating layer 124 surrounding the opening 126, which includes a lightemitting layer made of an organic light-emitting material. An upperelectrode 122 as a common electrode is formed on the insulating layer124 including the stacked structure 123. A reference numeral 12 denotesa gate electrode included in the TFT, a reference numeral 13 denotes agate insulating film included in the TFT, a reference numeral 14 denotesa source/drain region included in the TFT, a reference number 15 is achannel formation region included in the TFT, a reference numeral 17denotes a wiring, a reference numeral 31 denotes a protection film, areference numeral 32 denotes an adhesive layer, and a reference number33 denotes a second substrate, which will be described in detail inEmbodiment 1.

Since the stacked structures 123 are formed over the first substrate 11on which the TFTs are formed through the interlayer insulating layer 16,in the case of an organic EL display device of a so-called bottomsurface emitting type in which emitted light generated at the stackedstructures 123 is taken out from the side of the first substrate,taken-out regions of the emitted light are narrowed by the TFTs.Therefore, it is desirable to apply an organic EL display device of aso-called top-surface emitting type in which emitted light is taken outfrom the second substrate 33 opposite to the first substrate 11.

In case that the organic EL display device of the top-surface emittingtype is applied, the lower electrode 121 is usually made of a reflectionmaterial and the upper electrode 122 is made of a transparent conductivematerial or a semitransparent conductive material. However, thetransparent material such as an oxide of indium and tin (ITO) or anoxide of indium and zinc (IZO), and the semitransparent materialincluding a thin-film metal have a higher electric resistance value ascompared with metals and the like. Therefore, a voltage gradient occursin the upper electrode 122 as the common electrode, as a result, voltagetends to fall. When such voltage falling occurs, voltage to be appliedto the stacked structure 123 forming each sub pixel will be uneven,which significantly reduces the display performance such that lightemitting intensity at, for example, the central portion of a displayarea of the organic EL display device is reduced.

A means for addressing the above problems is well known in, for example,JP-A-2001-195008, or JP-A-2004-207217. In the technique disclosed inthese patent documents, an auxiliary wiring 125 which is divided fromthe stacked structure 123 by the insulating layer 124 is provided, andthe upper electrode 122 is formed from a portion over the stackedstructure 123 to a portion over the auxiliary wiring 125 through theinsulating layer 124. The auxiliary wiring 125 is made of a conductivematerial having a low electric resistance value such as metals.

The insulating layer 124 is often made of an organic material. After theinsulating layer 124 having the opening 126 is formed over theinsulating layer 16, plasma treatment using oxygen radical and the likeis performed for cleaning up the surface of the lower electrode 121exposed at the bottom of the opening 126. Organic matters and the likeon the surface of the lower electrode 121 exposed at the bottom of theopening 126 are removed by performing the plasma treatment. However, asthe result of performing the plasma treatment, the surface of theinsulation layer 124 is also activated. For example, the insulatinglayer 124 includes a polyimide resin, a contact angle between theinsulating layer 124 and water when the oxygen plasma treatment is notperformed is approximately 78 degrees, however, the contact anglebetween the insulating layer 124 and water after the oxygen plasmatreatment is performed is approximately 22 degrees.

To provide the auxiliary wiring 125 is useful because it prevents imagequality from being lowered due to the voltage falling of the upperelectrode 122. However, when the upper layer 124 is in the activatedstate as described above, particularly in case that the upper electrodeis made of a semitransparent conductive material including a thin-filmmetal, a portion of the upper electrode 122 (non-overlapping portion122′) on the insulating layer 124 connecting a portion of the upperelectrode 122 on the stacked structure 123 to a portion of the upperelectrode 122 on the auxiliary wiring 125 is degenerated when formingthe upper electrode 122 after the stacked structure 123 is formed, whichsignificantly lowers the conductivity. As a consequence, image qualitydeteriorates.

Thus, it is desirable to provide an organic EL display device havingexcellent display performance, including a configuration and a structurecapable of reliably preventing the degeneration of the portion of theupper electrode connecting the portion of the upper electrode on thestacked structure to the portion of the upper electrode on the auxiliarywiring.

SUMMARY

According to a first embodiment, there is provided an organicelectroluminescence display device (abbreviated to an organic EL displaydevice according to the first embodiment) including plural organicelectroluminescence elements (abbreviated to organic EL elements), eachhaving

(A) a lower electrode,

(B) an insulating layer having an opening, in which a lower electrode isexposed at the bottom of the opening,

(C) an auxiliary wiring,

(D) a stacked structure provided from a portion over the lower electrodeexposed at the bottom of the opening to a portion of the insulatinglayer surrounding the opening, including a light emitting layer made ofan organic light-emitting material, and

(E) an upper electrode, in which at least one layer of the stackedstructure partially contacts the auxiliary wiring, the insulating layerand the auxiliary wiring are provided in common to the plural organic ELelements, and the upper electrode covers the whole surface of thestacked structures and the auxiliary wiring forming the plural organicEL elements.

In the organic EL display device according to the first embodiment, aportion (overlapping portion) of at least one layer of the stackedstructure which contacts the auxiliary wiring may be formed on theauxiliary wiring (more specifically, on an edge portion of the auxiliarywiring). In the organic EL display device according to the firstembodiment including such preferred state, the stacked structure may beconfigured to touch the two auxiliary wirings, (specifically, to overlapwith edge portions of the two auxiliary wirings extending in paralleland sandwiching the stacked structure), though not limited thereto.

According to a second embodiment, there is provided an organicelectroluminescence display device (abbreviated to an organic EL displaydevice according to the second embodiment) including plural organicelectroluminescence elements, each having

(A) a lower electrode,

(B) an insulating layer having an opening, in which a lower electrode isexposed at the bottom of the opening,

(C) an auxiliary wiring,

(D) a stacked structure provided from a portion over the lower electrodeexposed at the bottom of the opening to a portion of the insulatinglayer surrounding the opening, including a light emitting layer made ofan organic light-emitting material, and

(E) an upper electrode, in which a portion of the upper electrodepositioned over the auxiliary wiring is electrically connected to theauxiliary wiring through a two-layer structure layer including a chargeinjection layer and a charge transport layer from below, the insulatinglayer and the auxiliary wiring are provided in common to plural organicEL elements, and the upper electrode covers the stacked structures andthe two-layer structure layer forming the plural organic EL elementswithout touching the insulating layer.

In the organic EL display device according to the second embodiment, thetwo-layer structure layer extends between the upper electrode and theinsulating layer and further, the two-layer structure layer extends alsobetween the stacked structure positioned over the lower electrode andthe upper electrode. In case that the two-layer structure layer extendsbetween the stacked structure and the upper electrode, specifically, thetwo-layer structure layer and the upper electrode formed thereon coverthe stacked structures forming the plural organic electroluminescenceelements. In this case, the two-layer structure layer and the upperelectrode formed thereon can be formed by the same process, which cansimplify the manufacturing process as well as reduces the number ofmasks to be used. In addition, in the organic EL display deviceaccording to the second embodiment, at least one layer of the stackedstructure may include a portion touching the auxiliary wiring.

In the organic EL display device according to the second embodimentincluding the above preferred state, it is preferable that voltagefalling between the auxiliary wiring and the upper electrode is equal toor less than 5 V when the current density of electric current flowing ata contact portion between the auxiliary wiring and the upper electrodeis equal to or less than 10 A/cm². Such preferred state can be achievedby the suitable selection of materials forming the two-layer structurelayer and the optimization of the area of the portion of the two-layerstructure layer which electrically connects the upper electrode and theauxiliary wiring.

Furthermore, in the organic EL display device according to the firstembodiment or the second embodiment including the preferred statesexplained as the above, the upper electrode is configured to be made ofa conductive material including magnesium (Mg), for example, a Mg—Agalloy, and the thickness of the upper electrode is configured to be 4 nmto 20 nm, preferably, 6 nm to 12 nm.

In the organic EL display device according to the first embodiment orthe second embodiment (hereinafter, sometimes simply referred to as thepresent application) including the preferred configuration or the stateexplained as the above, when the organic EL display device is acolor-display organic EL display device, respective organic EL elementsforming the organic EL display device form sub pixels. One pixelincludes three kinds of sub pixels which are a red light-emitting subpixel emitting red, a green light-emitting sub pixel emitting green anda blue light-emitting sub pixel emitting blue. Therefore, in this case,when the number of organic EL elements forming the organic EL displaydevice is N×M, the number of pixels is (N×M)/3.

In the organic EL display device according to the first embodiment, theupper electrode covers the whole surface of the stacked structures andthe auxiliary wiring forming the plural organic EL elements, andspecifically, it is preferable that the stacked structures and theauxiliary wiring forming N×M (namely, all) organic El elements arecovered by one sheet of upper electrode, though not limited thereto. Inthe organic EL display device according to the second embodiment, theupper electrode covers the stacked structures forming plural organic ELdisplay elements, and specifically, it is preferable that the stackedstructures forming N×M (namely, all) organic EL elements are covered byone sheet of upper electrode, though not limited thereto. In this case,it is more preferable that the stacked structures forming N×M (namely,all) organic EL elements are covered by one sheet of two-layer structurelayer.

In the organic EL display device according to the second embodiment,when the lower electrode is used as an anode electrode and the upperelectrode is used as a cathode electrode, the charge injection layerincluded in the two-layer structure layer is formed by an electroninjection layer and the charge transport layer is formed by an electrontransport layer. On the other hand, when the lower electrode is used asa cathode electrode and the upper electrode is used as an anodeelectrode, the charge injection layer included in the two-layerstructure layer is formed by a hole injection layer and the chargetransport layer is formed by a hole transport layer. Materials formingthese respective layers are configured to be the same known materialsforming the electron injection layer, the electron transport layer, thehole injection layer and the hole transport layer, and as an example,LiF can be cited as a material forming the electron injection layer, andelectron transport materials such as Bathophenanthroline, Bathocuproine(BCP) and Anthracene as materials forming the electron transport layer.Materials forming these respective layers may be the same as materialsforming a layer having the same function in the stacked structure or maybe different from them. It is preferable that the two-layer structurelayer is formed based on a vacuum deposition process which is a processin which energy of deposition particles is small to an extent notaffecting the stacked structure.

In the embodiment, when the organic EL display device is a top-surfaceemitting type and the lower electrode is used as the anode electrode, itis preferable that the lower electrode is made of a conductive materialwhose value of a work function is large as well as whose lightreflectance is high such as chromium (Cr), iron (Fe), cobalt (Co),nickel (Ni), copper (Cu), tantalum (Ta), tungsten (W), platinum (Pt) andgold (au). In addition, when a conductive material whose value of thework function is small as well as whose light reflectance is high suchas aluminum (Al), or alloys including aluminum is used, the lowerelectrode can be used as the anode electrode by providing a suitablehole injection layer to improve the hole injection ability. It is alsopreferable to apply a structure in which a transparent conductivematerial having excellent hole injection characteristics such as oxideof indium and tin (ITO) or oxide of indium and zinc (IZO) is stacked ona conductive material having high light reflectance. On the other hand,when the lower electrode is used as the cathode electrode, it ispreferable that the lower electrode is made of a conductive materialwhose value of the work function is small as well as whose lightreflectance is high, however, the lower electrode can be used as thecathode electrode by providing a suitable electron injection layer to aconductive material having high light reflectance used as the anodeelectrode to improve the electron injection ability. As a method offorming the lower electrode, a vapor deposition process such as anelectron beam deposition process, and a hot-filament deposition process,a sputtering process, a chemical vapor deposition process (CVD process),the combination of an ion-plating process and an etching process;various printing processes such as a screen printing process, an ink jetprinting process and a metal mask printing process; a plating process(an electroplating or an electroless plating process); a lift-offprocess; a laser ablation process; a Sol-Gel process and the like can becited.

On the other hand, when the organic EL display device is the top-surfaceemitting type and the upper electrode is used as the cathode electrode,it is preferable that the upper electrode is made of a conductivematerial whose value of the work function is small so as to allowemitted light to be transmitted therethrough as well as to allowelectrons to be efficiently injected with respect to the stackedstructure. Specifically, it is preferable to use a conductive film asthe upper electrode, which has high light transmittance such as a Mg—Agalloy thin film (for example, a metal or an alloy material whose lighttransmittance is 30% or more) as described above. Note that the upperelectrode is liable not to function as an electrode if the thickness ofthe upper electrode made of the Mg—Au alloy is not more than 4 nm. Ifthe thickness exceeds 20 nm, the electrode is liable not to be suitablefor the upper electrode because the light transmittance is reduced. Whenthe upper electrode is used as the anode electrode, it is preferablethat the upper electrode is made of a conductive material through whichemitted light is transmitted and whose value of the work function islarge. The upper electrode is preferably formed by a deposition processwhich is a process in which energy of deposition particles is small suchas the vacuum deposition process or a MOCVD process from a viewpointthat damages in the stacked structure is prevented from occurring. Ifdamages occur in the stacked structure, a non-emitting pixel (ornon-emitting sub pixel) which is called as a “dark spot” is liable to begenerated due to occurrence of leak current. In addition, it ispreferable that the formation of the stacked structure to the formationof the upper electrode is executed without being exposed to air from aviewpoint of preventing deterioration of the stacked structure due tomoisture in air. When the upper electrode is used as a cathodeelectrode, an electron injection layer having the same pattern as theupper electrode (for example, made of Lif which is extremely thin, thethickness of which is 0.3 nm) may be formed just under the upperelectrode, thereby increasing the electron injection ability, realizinglow drive voltage, high efficiency and long life of the organic ELelements.

In an embodiment, it is preferable that the insulating layer is made ofan insulating material having excellent flatness and low water-absorbingproperty for preventing deterioration of the stacked structure due tomoisture to keep light-emitting luminance, specifically, organicinsulating materials such as polyimide resin, photoresist materials andthe like can be cited.

In an embodiment, it is preferable that the auxiliary wiring is made ofa conductive material having low resistance, for example, metals such asaluminum (Al), silver (Ag), nickel (Ni), copper (Cu), chromium (Cr),tungsten (W), niobium (Nb), tantalum (Ta), molybdenum (Mo), gold (Au),titanium (Ti), cobalt (Co), zirconium (Zr), iron (Fe), platinum (Pt),and zinc (Zn), or alloys including the above metal elements (forexample, Al—Cu). It is possible to form the auxiliary wiring by usingthe above materials in a single layer or by staking them (for example, aCr/Cu/Cr stacked film or a Cr/Al/Cr stacked film). As a method offorming the auxiliary wiring, for example, a vapor deposition processsuch as an electron beam deposition process, and a hot-filamentdeposition process, a sputtering process, a CVD process, the combinationof an ion-plating process and an etching process; various printingprocesses such as a screen printing process, an ink jet printing processand a metal mask printing process; a plating process (an electroplatingor an electroless plating process); a lift-off process; a laser ablationprocess; a Sol-Gel process and the like can be cited. According to thevarious printing processes or the plating process, for example, abelt-shape auxiliary wiring or a lattice-shape auxiliary wiring can bedirectly formed.

According to an embodiment, the stacked structure includes alight-emitting layer made of an organic light-emitting material,specifically being formed by a stacked state of a hole transport layer,a light emitting layer and an electron transport layer, a stacked stateof a hole transport layer and a light emitting layer doubling as anelectron transport layer, a stacked state of a hole injection layer, ahole transport layer, a light emitting layer, an electron transportlayer and an electron injection layer.

Here, in the organic EL display device according to the firstembodiment, at least one layer of the stacked structure partiallycontacts the auxiliary wiring, and it is preferable that a layer havinga portion (more specifically, a portion overlapping with an edge portionof the auxiliary wiring) touching the auxiliary wiring (which is calledas an “auxiliary wiring contact layer” for convenience) is made to bethe above at-least one layer forming the stacked structure. That is tosay, when the stacked structure is formed by a stacked state of the holetransport layer, the light emitting layer and the electron transportlayer, the auxiliary wiring contact layer can be the hole transportlayer, the light emitting layer, the electron transport layer, (the holetransport layer+the light emitting layer), (the light emitting layer+theelectron transport layer), (the hole transport layer+the electrontransport layer), or (the hole transport layer+the light emittinglayer+the electron transport layer). In addition, when the stackedstructure is formed by a stacked state of the hole transport layer andthe light emitting layer doubling as the electron transport layer, theauxiliary wiring contact layer can be the hole transport layer, thelight emitting layer doubling as the electron transport layer or (thehole transport layer+the light emitting layer doubling the electrontransport layer). Furthermore, when the stacked structure is formed by astacked state of the hole injection layer, the hole transport layer, thelight emitting layer, the electron transport layer and the electroninjection layer, the auxiliary wiring contact layer can be one layer ofthe five layers, combination of optional two layers of the five layers,combination of optional three layers of the five layers, combination ofoptional four layers of the five layers or all five layers. Generally,when the stacked structure is formed by a stacked state of L-layers, theauxiliary wiring contact layer can be one layer of the L-layers, allL-layers or combinations of optional layers of two layers or more in theL-layers.

According to an embodiment, as a method of forming the stacked structureor the two-layer structure layer, a physical vapor deposition process(PVD process) such as a vacuum vapor deposition process; printingprocesses such as a screen printing or an ink jet printing process; alaser transfer process in which the stacked structure or the two-layerstructure layer is transferred by irradiating laser to a stacked stateof a laser absorption layer formed on a substrate for transfer and thestacked structure or the two-layer structure layer to divide the stackedstructure or the two-layer structure layer on the laser absorptionlayer, and various coating process can be cited. When the stackedstructure or the two-layer structure layer is formed based on the vacuumdeposition process, for example, a so-called metal mask is used andmaterials passed through openings provided at the metal mask aredeposited to obtain the stacked structure or the two-layer structurelayer. In the organic EL display device according to the firstembodiment, it is preferable that the length of the opening provided atthe metal mask is longer than the interval between points where thestacked structure contacts the auxiliary wiring, for example, when twopoints of the stacked structure touch the auxiliary wiring, so thatportions of the stacked structure which touch the auxiliary wiring arepositively formed even when the positional displacement of the metalmask occurs.

The lower electrode included in the organic EL is formed, for example,on the interlayer insulating layer. The interlayer insulating layercovers the organic EL element driver unit formed on the first substrate.The organic EL element driver unit includes one or plural thin-filmtransistors, and the TFT is electrically connected to the lowerelectrode through a contact plug provided in the interlayer insulatingfilm. As materials for forming the interlayer insulating layer, SiO²materials such as SiO², BPSG, PSG, BSG, AsSG, PbSG, SiON, SOG(spin-on-glass), low melting glass, glass paste; SiN materials; orinsulating resins such as polyamide can be used by itself or bycombining them appropriately. For the formation of the interlayerinsulating layer, known processes such as the CVD process, the coatingprocess, the sputtering process, various printing processes can be used.

It is preferable that an insulating or conductive protection film isprovided on the upper electrode for preventing moisture from reachingthe stacked structure. The protection film is preferably formed based ona deposition process in which energy of deposition particles is smallparticularly such as a vacuum deposition process, or formed by a MOCVDprocess, which can reduce effects on the base. It is also preferablethat the protection film is deposited by setting deposition temperatureto be constant for preventing reduction of luminance due todeterioration of the stacked structure, and further, it is preferablydeposited under conditions minimizing the stress on the protection filmfor preventing the peeling of the protection film. In addition, it ispreferable that the protection film is formed without exposing the upperelectrode to air, which prevents deterioration of the stacked structuredue to moisture or oxygen in air. In case that the organic EL displaydevice is the top-surface emitting type, the protection film ispreferably made of a material through which, for example, more than 80%of light generated in the stacked structure is transmitted,specifically, inorganic-amorphous insulating materials such as amorphoussilicon (α-Si), amorphous silicon carbide (α-SiC), amorphous siliconnitride (α-Si_(1-X)-N_(x)), amorphous silicon oxide (α-Si_(1-y)O_(y)),amorphous carbon (α-C) can be cited. Since such inorganic-amorphousinsulating materials do not generate grains, water permeability is lowand can form the good protection film. When the protection film is madeof a conductive material, the protection film may be made of atransparent conductive material such as ITO or IZO. The second substrateis arranged over the protection film, and the protection film and thesecond substrate are adhered by using a UV cure adhesive or a heat cureadhesive.

As materials for the first substrate and the second substrate,high-distortion point glass, soda-lime glass Na₂O/CaO/SiO₂),borosilicate glass (Na₂O/B₂O₃/SiO₂), forsterite (2MgO/SiO₂), lead glass(Na₂O/PbO/SiO₂), various plastic substrates can be cited. The materialfor the first substrate and the material for the second substrate may bethe same, or may be different from each other.

In the organic EL display device according to the first embodiment, thestacked structure has a portion (overlapping portion) touching theauxiliary wiring, and the upper electrode covers the whole surface ofthe stacked structures and the auxiliary wiring forming plural organicEL elements. Therefore, it is certain that there does not exist theinsulating layer just under a portion of the upper electrode connectinga portion of the upper electrode over the stacked structure to a portionof the upper electrode over the stacked structure. That is, the portionof the upper electrode connecting the portion of the upper electrodeover the stacked structure to the portion of the upper electrode overthe auxiliary wiring is formed at least on one layer of the plurallayers included in the stacked structure. In the organic EL displaydevice according to the second embodiment, the upper electrode coversthe stacked structures and the two-layer structure layer forming pluralorganic electroluminescence elements without touching the insulatinglayer. Therefore, a portion of the upper electrode connecting a portionof the upper electrode over the stacked structure and a portion of theupper electrode on the auxiliary wiring does not degenerate, therebyproviding the organic EL display device having excellent displayperformance. In addition, in the organic EL display device according tothe second embodiment, the upper electrode and the auxiliary wiring areelectrically connected through the two-layer structure layer including acharge injection layer and a charge transport layer from below,therefore, charges (electrons or holes) are transported from theauxiliary wiring to the upper electrode through the charge injectionlayer and the charge transport layer without losing large voltage, as aresult, voltage rising at an electrical connection portion between theupper electrode and the auxiliary wiring can be suppressed as well asmanufacturing processes can be simplified according to the state of thetwo-layer structure layer.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic partial cross-sectional view of an organicelectroluminescence display device according to Embodiment 1;

FIG. 2 is a partial plan view schematically showing arrangement ofstacked structures, an auxiliary wiring, an insulating layer and thelike in the organic electroluminescence display device according toEmbodiment 1;

FIG. 3 is a partial plan view schematically showing arrangement of alower electrode, openings, the insulating layer and the like in theorganic electroluminescence display device according to Embodiment 1;

FIG. 4 is a partial plan view schematically showing arrangement of thelower electrode, interlayer insulating layers and the like in theorganic electroluminescence display device according to Embodiment 1;

FIG. 5A, FIG. 5B and FIG. 5C are schematic partial cross-sectional viewsof the first substrate and the like for explaining an outline of amanufacturing method of the organic electroluminescence display deviceaccording to Embodiment 1;

FIG. 6A and FIG. 6B are schematic partial cross-sectional views of thefirst substrate and the like for explaining the outline of themanufacturing method of the organic electroluminescence display deviceaccording to Embodiment 1 continued from FIG. 5C;

FIG. 7A and FIG. 7B are schematic partial cross-sectional views of thefirst substrate and the like for explaining the outline of themanufacturing method of the organic electroluminescence display deviceaccording to Embodiment 1 continued from FIG. 6B;

FIG. 8 is a schematic partial cross-sectional view of an organicelectroluminescence display device according to Embodiment 2;

FIG. 9A and FIG. 9B are schematic partial cross-sectional views of thefirst substrate and the like for explaining an outline of amanufacturing method of the organic electroluminescence display deviceaccording to Embodiment 2;

FIG. 10A and FIG. 10B are schematic partial cross-sectional views of amodification example of the organic electroluminescence display deviceaccording to Embodiment 2;

FIG. 11A and FIG. 11B are schematic partial cross-sectional views of amodification the organic electroluminescence display device according toEmbodiment 1,

FIG. 12 is a schematic partial cross-sectional view of an organicelectroluminescence display device showing a modification of a structureof an overlapping portion over a part of the insulating layer; and

FIG. 13 is a schematic partial cross-sectional view of an organicelectroluminescence display device of a related art; and

FIG. 14 is a partial plan view schematically showing arrangement of astacked structure, an auxiliary wiring and an insulating layer and thelike in the organic electroluminescence display device of the relatedart.

DETAILED DESCRIPTION

Hereinafter, the embodiments will be explained in embodiments withreference to the drawings.

Embodiment 1

Embodiment 1 relates to an organic EL display device according to afirst embodiment. A schematic partial cross-sectional view of theorganic EL display device of Embodiment 1 is shown in FIG. 1, and anarrangement of a stacked structure, an auxiliary wiring, an insulatinglayer and the like in the organic EL display device of Embodiment 1 isschematically shown in partial plan views of FIG. 2, FIG. 3 and FIG. 4.The organic EL display device of Embodiment 1 or later-describedEmbodiment 2 is a color-display organic EL display device of an activematrix type, which is a top-surface emitting type. That is, light isemitted through an upper electrode.

The organic EL display device of Embodiment 1 or later-describedEmbodiment 2 has plural (for example, N×M=2880×540) organic EL elements10, 10A. One organic EL element 10, 10A forms one sub pixel. Therefore,the organic EL display device has (N×M)/3 pixels. One pixel includesthree kinds of sub pixels which are a red light-emitting sub pixelemitting red color, green light-emitting sub pixel emitting green and ablue light-emitting sub pixel emitting blue color.

Each organic EL element 10, 10A in the organic EL display device ofEmbodiment 1 or later-described Embodiment 2 includes

(A) a lower electrode 21,

(B) an insulating layer 24 including an opening 26 in which a lowerelectrode 21 is exposed at the bottom of the opening 26,

(C) an auxiliary wiring 25, 45,

(D) a stacked structure 23, 43 provided from a portion over the lowerelectrode 21 exposed at the bottom of the opening 26 to a portion 24′ ofthe insulating layer 24 surrounding the opening 26, including alight-emitting layer made of an organic light emitting material and

(E) an upper electrode 22, 42.

In the organic EL display device of Embodiment 1, at least one layer ofthe stacked structure 23 (in Embodiment 1, specifically, the wholeplural layers forming the stacked structure 23) includes a portiontouching the auxiliary wiring 25 (a portion overlapping with an endportion of the auxiliary wiring 25), the insulating layer 24 and theauxiliary wiring 25 are provided in common to plural organic EL elements10, and the upper electrode 22 covers the whole surface of the stackedstructure 23 and the auxiliary wiring 25 forming plural (specifically,N×N pieces) organic EL elements without touching the insulating 24.Here, a portion touching the auxiliary wiring 25 (overlapping portion23′) of at least one layer of the stacked structure 23 (in Embodiment 1,specifically, the whole plural layers forming the stacked structure 23)is formed over an edge portion of the auxiliary wiring 25. The stackedstructure 23 contacts two auxiliary wirings 25 extending in parallel andsandwiching the stacked structure 23. More specifically, the stackedstructure 23 overlaps with edge portions of two auxiliary wirings 25extending in parallel and sandwiching the stacked structure 23.

In Embodiment 1, or later-described Embodiment 2, the lower electrode 21is used as an anode electrode, and the upper electrode 22 is used as acathode electrode. The lower electrode 21 is made of chromium (Cr) andthe upper electrode 22 is made of a conductive material includingmagnesium (Mg), specifically, a Mg—Ag alloy having a thickness of 10 nm.Note that an average light transmittance of the upper electrode 22 in arange from wavelength 450 nm to 650 nm is 50.3%. The auxiliary wiring25, 45 is made of a conductive material having low resistance such asaluminum (Al). The lower electrode 21 and the auxiliary wiring 25, 45are formed based on combination of a vacuum deposition process and anetching process. The upper electrode 22, 42 is deposited particularly bya deposition process in which energy of deposition particles is smallsuch as the vacuum deposition process.

In Embodiment 1, or later-described Embodiment 2, the insulating layer24 is made of an insulating material having excellent flatness as wellas having a low water absorption coefficient for preventingdeterioration due to moisture and for maintaining light-emittingluminance in the stacked structure, specifically, a polyimide resin. Inaddition, the stacked structure 23, 43 is formed by a structure ofstacking a hole transport layer and a light-emitting layer doubling asan electron transport layer, or a structure of stacking the holetransport layer, the light-emitting layer and the electron transportlayer, however, shown by one layer in the drawing.

In Embodiment 1, or later-described Embodiment 2, the lower electrode 21included in the organic EL element is provided on an interlayerinsulating layer 16 (more specifically, an upper interlayer insulatinglayer 16B) including SiO₂ formed based on a CVD process. The interlayerinsulating layer 16 covers an organic EL element driver unit formed onthe first substrate 11. The organic EL element driver unit includesplural TFTs, and each TFT and the lower electrode 21 are electricallyconnected through a contact plug 18, a wiring 17 and a contact plug 17Awhich are provided in the interlayer insulating layer (morespecifically, the upper interlayer insulating layer 16B). In thedrawing, one TFT is shown for one organic EL element driver unit.

In Embodiment 1, or later-described Embodiment 2, an insulatingprotection film 31 including silicon nitride (Si_(1-x)N_(x)) is providedon the upper electrode 22, 42 by using the vacuum deposition process forthe purpose of preventing the moisture from reaching the stackedstructure 23, 43. A second substrate 33 is arranged over the protectionfilm 31, and the protection film 31 and the second substrate 33 areadhered by an adhesive layer 32 made of a UV cure adhesive.

In Embodiment 1, or later-described Embodiment 2, the first substrate 11and the second substrate 33 are made of soda-lime glass.

In Embodiment 1, or later-described Embodiment 2, each stacked structure23, 43 specifically includes a stacked structure 23R in an organic ELelement forming a red light-emitting sub pixel, a stacked structure 23Gin an organic EL element forming a green light-emitting sub pixel and astacked structure 23B in an organic EL element forming a bluelight-emitting sub pixel.

An outline of a method of manufacturing the organic EL display device ofEmbodiment 1 will be explained with reference to FIG. 2 to FIG. 4, FIG.5A to FIG. 5C, FIG. 6A, 6B and FIG. 7A, 7B as follows.

[Process-100]

First, a TFT is fabricated at each sub pixel by a well-known method. TheTFT includes a gate electrode 12 formed on the first substrate 11, agate insulating film 13 formed over the first substrate 11 and the gateelectrode 12, source/drain regions 14 provided on a semiconductor layerformed on the gate insulating film 13, and a channel formation region 15corresponding to a portion between the source/drain regions 14 in thesemiconductor layer positioned over the gate electrode 12. In the shownexample, the TFT is a bottom-gate type, however, a top-gate type TFT isalso preferable. The gate electrode 12 of the TFT is connected to ascanning circuit (not shown). Next, a lower interlayer insulating layer16A including SiO₂ is deposited over the first substrate 11 by the CVDprocess so as to cover the TFT. Then, an opening 16′ is formed in thelower interlayer insulating layer 16A based on a photolithographytechnique or an etching technique (refer to FIG. 5A).

[Process-110]

Next, the wiring 17 including aluminum is formed on the lower interlayerinsulating layer 16A based on combination of the vacuum depositionprocess and the etching process. The wiring 17 is electrically connectedto the source/drain regions 14 of the TFT through the contact plug 17Aformed in the opening 16′. The wiring 17 is connected to a signal supplycircuit (not shown). Then, the upper inter insulating layer 16Bincluding SiO₂ is deposited over the whole surface by the CVD process.Next, an opening 18′ is formed over the upper interlayer insulatinglayer 16B based on the photolithography technique and the etchingtechnique (refer to FIG. 5B).

[Process-120]

After that, a lower electrode 21 made of chromium is formed on the upperinterlayer insulating layer 16B based on combination of the vacuumdeposition process and the etching process (refer to FIG. 5C and FIG.4). The lower electrode 21 is electrically connected to the wiring 17through the contact plug 18 provided in the opening 18′.

[Process-130]

Next, an insulating layer 24 having an opening 26, in which the lowerelectrode 21 is exposed at the bottom of the opening 26 is formed on theinterlayer insulating layer 16 including the lower electrode 21 (referto FIG. 6A and FIG. 3). Specifically, the insulating layer 24 made ofpolyimide resin having a thickness of 1 μm is formed on the interlayerinsulating layer 16 and over the periphery of the lower electrode 21based on a spin coating process and the etching process. It ispreferable that a portion 24′ of the insulating layer 24 surrounding theopening 26 forms a gentle slope.

[Process-140]

After that, an auxiliary wiring 25 is formed on the insulating layer 24based on the vacuum deposition process and the etching technique (referto FIG. 6B). The insulating layer 24 and the auxiliary wiring 25 areprovided in common to N×M organic EL elements. The auxiliary wiring 25is formed on opposed two edges in a kind of protrusion of the insulatinglayer 24 surrounding the stacked structure 23.

[Process-150]

Next, a stacked structure 23 is formed from a portion over the lowerelectrode 21 exposed at the bottom of the opening 26 to the portion 24′of the insulating layer 24 surrounding the opening 26 (refer to FIG. 7Aand FIG. 2). In the stacked structure 23, for example, a hole transportlayer and a light-emitting layer doubling as an electron transport layerwhich are made of an organic material are sequentially stacked. Or, inthe stacked structure 23, the hole transport layer, the light-emittinglayer and the electron transport layer which are made of an organicmaterial are sequentially stacked. The stacked structure 23 contacts theauxiliary wiring 25 as a whole, however, a portion of the stackedstructure 23 touching the auxiliary wiring 25 is formed on an edgeportion of the auxiliary wiring 25. The stacked structure 23 contactstwo auxiliary wirings 25.

Specifically, a plasma treatment is performed for removing organicextraneous matters and for improving hole injection ability of thesurface of the lower electrode 21. As gas to be introduced, oxygen gas,nitrogen gas and argon gas can be cited, and in Embodiment 1, oxygenplasma processing of the processing power 100 W and processing time of180 seconds is performed. The surface of the insulating layer 24 is in achemically active state by the oxygen plasma processing.

Next, the organic material is vacuum-deposited in a state in which theinsulating layer 24 is used as a kind of spacer and a metal mask (notshown) for forming the stacked structure 23 which configures each subpixel is placed at the protrusion (in which the auxiliary wiring 25 isprovided) of the insulating layer 24 based on resistance heating. Theorganic material passes through an opening provided on the metal maskand is deposited from the portion over the lower electrode 21 exposed atthe bottom of the opening 26 forming the sub pixel to the portion 24′ ofthe insulating layer 24 surrounding the opening 26, and further, over apart of the auxiliary wiring 25.

In the stacked structure (organic layer) 23G in the organic EL elementforming the green light-emitting pixel, for example, m-MTDATA[4,4′,4″-tris(3-methylphenylphenylamino) triphenylamine] is deposited ina film thickness of 25 nm as a hole injection layer. Next, for example,α-NPD[4,4-bis(N-1-naphthyl-N-phenylamino)biphenyl] in a film thicknessof 30 nm as a hole transport layer. Subsequently, for example, Alq3[tris(8-quinolinolato) aluminum (III)] is deposited in a film thicknessof 50 nm as the light-emitting layer doubling as the electron transportlayer. These layers are sequentially deposited in the same vacuumdeposition apparatus.

In the stacked structure (organic layer) 23B in the organic EL elementforming the blue light-emitting sub pixel, for example, m-MTDATA isdeposited in a film thickness of 18 nm as the hole injection layer.Next, for example, α-NPD is deposited in a film thickness of 30 nm asthe light-emitting layer doubling as the hole transport layer. Further,for example, Bathocuproine[2,9-dimethyl-4,7-diphenyl-1,10phenanthroline]is deposited in a film thickness of 14 nm as a hole block layer, then,for example, Alq3 is deposited in a film thickness of 30 nm as theelectron transport layer. These layers are sequentially deposited in thesame vacuum deposition apparatus.

Furthermore, in the stacked structure (organic layer) 23R in the organicEL element forming the red light-emitting sub pixel, for example,m-MTDATA is deposited in a film thickness of 55 nm as the hole injectionlayer. Next, for example, α-NPD is deposited in a film thickness of 30nm as the hole transport layer. Further, for example, BSB-BCN [2,5-bis{(N-methoxyphenyl-N-phenylamino)styryl}benzene-1,4-dicarbonitrile] isdeposited as the light emitting layer, then, for example, Alq3 isdeposited in a film thickness of 30 nm as the electron transport layer.These layers are sequentially deposited in the same vacuum depositionapparatus.

[Process-160]

After that, the upper electrode 22 is formed on the whole surface of thedisplay area (refer to FIG. 7B). The upper electrode 22 covers the wholesurface of the stacked structures 23 and the auxiliary wiring 25included in N×M organic EL elements. However, the upper electrode 22 isinsulated from the lower electrode 21 by the stacked structure 23 andthe insulating layer 24. The upper electrode 22 is formed based on thevacuum deposition process which is a deposition process in which energyof deposition particles is small to an extent not affecting the stackedstructure 23. It is also preferable that an electron injection layer(for example, made of Lif having a thickness of 0.3 nm) for increasingan electron injection ability to the stacked structure 23 is formedbetween the stacked structure 23, the auxiliary wiring 25 and the upperelectrode 22. In addition, the upper electrode 22 is sequentially formedin the same vacuum deposition apparatus as the formation of the stackedstructure 23 without exposing the stacked structure 23 to air, therebypreventing deterioration of the stacked structures 23 due to moistureand oxygen in air. Specifically, Mg—Ag co-deposited film (volume ratio10:1) is formed in a film thickness of 10 nm, thereby obtaining theupper electrode 22.

[Process-170]

Next, the insulating protection film 31 including silicon nitride(Si_(1-X)N_(X)) is formed on the upper electrode 22 based on the vacuumdeposition process. The formation of the protection film 31 is performedsequentially in the same vacuum deposition apparatus as the formation ofthe upper electrode 22 without exposing the upper electrode 22 to air,thereby preventing deterioration of the stacked structures 23 due tomoisture and oxygen in air. After that, the protection film 31 and thesecond substrate 33 are adhered by the adhesive layer 32 made of a UVcure adhesive. Lastly, the organic EL display device of Embodiment 1 canbe completed by performing connection to external circuits.

In the organic EL display device in Embodiment 1, the auxiliary wiring25 is provided, which can suppress the generation of voltage falling inthe display area of the upper electrode 22 formed in a state of coveringthe whole surface of the display area even when the sheet resistance ofthe upper electrode 22 is high. As a result, it is possible touniformize the light-emitting intensity of the organic EL elements inthe display area. In addition, the portion at which the stackedstructure 23 contacts the auxiliary wiring 25 (overlapping portion 23′)is formed at the edge portions of the auxiliary wiring 25, that is, theupper electrode 22 does not directly touch the insulating layer 24,therefore, the upper electrode 22 can be prevented from beingdegenerated by the insulating layer 24. Therefore, it is possible topositively prevent problems such as lowering of image quality fromoccurring. The power consumption can be also reduced by proving theauxiliary wiring 25.

Specifically, in the organic EL display device in Embodiment 1, normalemission probability is 99.9%, and good emission characteristics can beobtained. On the other hand, as the schematic partial cross-sectionalview is shown in FIG. 13 and the schematic partial plan view is shown inFIG. 14, the stacked structure 123 does not have a portion touching theauxiliary wiring 125, and the portion of the upper electrode 122connecting the portion of the upper electrode 122 on the stackedstructure 123 to the portion of the upper electrode 122 on the auxiliarywiring 125 is entirely formed on the insulating layer 124. When theorganic EL display device having the structure and the configuration ofthe related art was fabricated as a comparative example and the normalemission probability was checked, the probability was 78.4% and thefrequency at which the abnormality occurs was high. Such abnormalemission is caused by high resistance of the upper electrode 122 on theinsulating layer 124 which has received chemical degeneration(alteration).

Embodiment 2

Embodiment 2 relates to an organic EL display device according to asecond embodiment. A schematic partial cross-sectional view of theorganic EL display device of Embodiment 2 is shown in FIG. 8.

In the organic EL display device of Embodiment 2, a portion 42A of anupper electrode 42 positioned over an auxiliary wiring 45 iselectrically connected to the auxiliary wiring 45 through a two-layerstructure layer 61 (shown in one layer in the drawing) including acharge injection layer and a charge transport layer from below. Theinsulating layer 24 and the auxiliary wiring 45 are provided in commonto plural organic EL elements 10A, and the upper electrode 42 coversstacked structures 43 forming the plural organic EL elements 10A and thetwo-layer structure layer 61 without touching the insulating layer 24.In the organic EL display device of Embodiment 2, the lower electrode 21is used as an anode electrode and the upper electrode 42 is used as acathode electrode, therefore, the charge injection layer included in thetwo-layer structure layer 61 is formed by an electron injection layer,more specifically, Lif having a thickness of 0.3 nm, and the chargetransport layer is formed by an electron transport layer, moreparticularly, Bathocuproine (BCP) having a thickness of 5 nm.

The two-layer structure layer 61 extends between a portion 42B of theupper electrode 42 and the insulating layer 24. The portion 42B ispositioned between the portion 42A of the upper electrode 42 positionedover the auxiliary wiring 45 and a portion 42C of the upper electrode 42which covers the stacked structure 43. Further, the two-layer structurelayer 61 extends also between the portion of the stacked structure 43positioned over the lower electrode 21 and the upper electrode 42.Specifically, the two-layer structure layer 61 and the upper electrode42 formed thereover cover the whole surface of the stacked structures 43forming the plural organic EL elements and the auxiliary wiring 45,further, the insulating layer 24.

An outline of a method of manufacturing the organic EL display device ofEmbodiment 2 will be explained with reference to FIG. 9A and FIG. 9B.

[Process-200]

First, the TFT is fabricated by each sub pixel on the first substrate 11by the well-known method in the same manner as [Process-100] ofEmbodiment 1. Next, the wiring 17 is formed over the lower interlayerinsulating layer 16A in the same manner as [Process-110] of Embodiment1, depositing the upper interlayer insulating layer 16B including SiO₂over the whole surface by the CVD process and forming the opening 18′ onthe upper interlayer insulating layer 16B based on the photolithographytechnique and the etching technique. After that, the lower electrode 21including chromium is formed over the upper interlayer insulating layer16B in the same manner as [Process-120] of Embodiment 1. Next, theinsulating layer 24 having the opening 26, in which the lower electrode21 is exposed at the bottom of the opening 26 is formed over theinterlayer insulating layer 16 including the lower electrode 21 in thesame manner as [Process-130] of Embodiment 1. After that, the auxiliarywiring 45 is formed on the insulating layer 24 in the same manner as[Process-140] of Embodiment 1. Accordingly, the same structure as shownin FIG. 6B can be obtained.

[Process-210]

In substantially the same manner as [Process-150] of Embodiment 1, thestacked structure 43 is formed at a portion from the portion of thelower electrode 21 exposed at the bottom of the opening portion 26 tothe portion 24′ of the insulating layer 24 surrounding the opening 26(refer to FIG. 9A). In the stacked structure 43, for example, the holetransport layer made of an organic material and the light-emitting layerdoubling as the electron transport layer are sequentially stacked in thesame manner as Embodiment 1. Or, in the stacked structure 43, the holetransport layer made of an organic material, the light-emitting layerand the electron transport layer are sequentially stacked. The stackedstructure 43 is formed over the portion 24′ of the insulating layer 24surrounding the opening 26, however, it does not touch the auxiliarywiring 45, which is different from Embodiment 1.

Specifically, in the same manner as Embodiment 1, first, the plasmatreatment is performed for removing organic extraneous matters and forimproving hole injection ability of the surface of the lower electrode21.

Next, the organic material is vacuum-deposited in a state in which theinsulating layer 24 is used as a kind of spacer and a metal mask (notshown) for forming the stacked structure 43 which configures each subpixel is placed at the protrusion (in which the auxiliary wiring 25 isprovided) of the insulating layer 24 based on resistance heating. Theorganic material passes through an opening provided on the metal maskand is deposited from the portion over the lower electrode 21 exposed atthe bottom of the opening 26 forming the sub pixel to the portion 24′ ofthe insulating layer 24 surrounding the opening 26.

The structure of the stacked structure (organic layer) in the organic ELelement forming the green light-emitting sub pixel, the structure of thestacked structure (organic layer) in the organic EL element forming theblue light-emitting sub pixel and the structure of the stacked structure(organic layer) in the organic EL element forming the red light-emittingsub pixel can be the same as Embodiment 1.

[Process-220]

After that, the two-layer structure layer 61 including the chargeinjection layer and the charge transport layer from below is formed onthe whole surface of the display area by vacuum-depositing the organicmaterial based on the resistance heating (refer to FIG. 9B). Since thetwo-layer structure layer 61 is to be formed on the whole surface, amask or the like for forming the two-layer structure layer 61 is notnecessary, which simplifies the manufacturing process as well asdecreases the number of masks to be used. The two-layer structure layer61 is formed based on the vacuum deposition process in which energy ofdeposition particles is small to an extent not affecting the stackedstructure 43.

[Process-230]

After that, the upper electrode 42 is formed on the whole surface of thedisplay area in the same manner as [Process-160] of Embodiment 1. Theupper electrode 42 covers the whole surface the stacked structures 43and the auxiliary wiring 45 forming N×M organic EL elements. It is alsopreferable that an electron injection layer (made of, for example, Lifhaving a thickness of 0.3 nm) for increasing the electron injectionability to the stacked structure 43.

[Process-240]

Subsequently, in the same manner as [Process-170] of Embodiment 1, theinsulating protection film 31 including silicon nitride (Si_(1-x)N_(x))is formed on the upper electrode 42 by the vacuum deposition process,then, the protection film 31 and the second substrate 33 are adhered bythe adhesive layer 32 made of a UV cure adhesive. Lastly, the organic ELdisplay device of Embodiment 2 can be completed by performing connectionto external circuits.

The auxiliary wiring 45 and the upper electrode 42 are electricallyconnected through the two-layer structure layer 61, however, it ispreferable that voltage falling is small as much as possible from aviewpoint suppressing power consumption and heat generation of theorganic EL display device. Generally, the area of the electricalconnection portion between the auxiliary wiring 45 and the upperelectrode 42 (hereinafter, referred to as “contact portion”) isapproximately 1/100 to 1/1000 of the area of the electrical connectionportion between the upper electrode 42 and the stacked structure 43,therefore, the current density of electric current flowing at thecontact portion is approximately 100 times or 1000 times as much as thecurrent density of electric current flowing at the electrical connectionportion between the upper electrode 42 and the stacked structure 43.Even in such a condition, it is necessary to realize sufficient chargemovement, specifically, it is preferable that voltage falling betweenthe auxiliary wiring 45 and the upper electrode 42 is 5 V or less whenthe current density of electric current flowing between the auxiliarywiring 45 and the upper electrode 42 is 10 A/cm² or less at the contactportion.

In order to obtain the above condition, it is necessary that the chargetransport layer (electron transport layer) included in the two-layerstructure layer 61 has high electron mobility, in which electrons areeasily injected to the upper electrode 42 from the auxiliary wiring 45through the charge injection layer (electron injection layer). Theelectrons are injected from the upper electrode 42 to the stackedstructure 43 through the two-layer structure layer 61, as a result, thestacked structure 43 emits light, therefore, it is preferable that thecharge transport layer (electron transport layer) is made of an materialwhich keeps characteristics of the organic EL element in good conditionand is deposited by the deposition method in which characteristics ofthe organic EL element can be kept in good condition. Specifically,electron transport materials such as Bathocuproine (BCP),Bathophenanthroline and Anthracene can be cited.

In Embodiment 2, the charge transport layer (specifically, electrontransport layer) included in the two-layer structure layer 61 is made ofBathocuproine (BCP), therefore, the rise of drive voltage necessary forachieving the same luminance is suppressed to approximately 2.5 V ascompared with the organic EL display device of the above comparativeexample.

Also in the organic EL display device of Embodiment 2, the auxiliarywiring 45 is provided, in addition, the auxiliary wiring 45 and theupper electrode 42 are electrically connected through the two-layerstructure layer 61, therefore, occurrence of voltage falling in thedisplay area of the upper electrode 42 formed in a state of covering thewhole surface of the display area can be suppressed, even when the sheetresistance of the upper electrode 42 is high. As a result, it ispossible to uniformize the light emitting intensity of the organic ELelements in the display area. In addition, the two-layer structure layer61 exists between the insulating layer 24 and the upper electrode 42,and the upper electrode 42 does not directly touch the insulating layer24, which can positively suppress the upper electrode 42 to bedegenerated by the insulating layer 24. Therefore, it is possible toreliably prevent occurrence of problems such as occurrence ofdeterioration of image quality. It is also possible to reduce the powerconsumption by proving the auxiliary wiring 45.

The configuration and the structure of the two-layer structure layer 61are not limited to the configuration and the structure shown in FIG. 8.As shown in FIG. 10A, it is preferable that at least one layer of thestacked structure 43 (in the shown example, all plural layers formingthe stacked structure 43) may extend between the portion 42B of theupper electrode 42 and the insulating layer 24. The portion 42B ispositioned between the portion 42A of the upper electrode 42 positionedover the auxiliary wiring 45 and a portion 42C of the upper electrode 42which covers the stacked structure 43. In the shown example, the stackedstructure 43 includes portions touching the auxiliary wiring 45(portions overlapping with edge portions of the auxiliary wiring 45).The example shown in FIG. 10B is different from the example shown inFIG. 10A in a point in which the two-layer structure layer 61 is formedonly at the auxiliary wiring 45 and in the vicinity thereof. That is tosay, the stacked structure 43 is formed between the portion 24′ of theinsulating layer 24 and the upper electrode 42, and the upper electrode42 does not directly touch the insulating layer 24. In the aboveexamples, it is also preferable that the stacked structure 43 is formedafter the two-layer structure layer 61 is formed though not shown, andin such case, the stacked layer 43 is formed over the two-layerstructure layer 61.

Certain preferred embodiments have been explained. However, the presentapplication is not limited to these embodiments. The configuration andthe structure of the organic EL display device or the organic EL displayelement in the embodiments and materials forming the organic EL displaydevice or the organic EL display element have been explained asexamples, which can be suitably changed.

In the embodiments, a kind of protrusion is provided at the edge portionof the auxiliary wiring 25, and the overlapping portion 23′ of thestacked structure is provided on the protrusion, however, it is alsopreferable that an overlapping portion of the stacked structures isprovided on a liner-line edge portion of the auxiliary wiring, extendingthe whole length direction of the auxiliary wiring. It is alsopreferable that the auxiliary wiring is formed so as to surround allfour sides of one sub pixel and that an overlapping portion of thestacked structure is provided over the whole edge portions of theauxiliary wiring formed so as to surround the four sides of one subpixel. In addition, it is preferable that the stacked structure contactsone auxiliary wiring in some cases. In the embodiments, the insulatinglayer 24 has a shape including protrusions, however, the shape of theinsulating layer 24 is not limited to the shape, and it is alsopreferable to apply a configuration in which the top face of theinsulating layer 24 is in the same level as the top face of the stackedstructure 23.

Through the auxiliary wiring 25, 45 is formed on the insulating layer 24in the embodiments, it is also preferable that the auxiliary wiring 25,45 is provided on the interlayer insulating layer 16 when the lowerelectrode 21 is provided, an opening is provided at the insulating layer24 over the auxiliary wiring 25, 45 and the stacked structure 23, 43extends from a portion over the insulating layer 24 to the auxiliarywiring 25, 45 (refer to a schematic partial cross-sectional view of FIG.11A). Or, it is preferable that the auxiliary wiring 25, 45 is providedwhen the formation of the wiring 17 at the same time (refer to schematicpartial cross-sectional view in FIG. 11B). The configuration and thestructure in these modifications can be applied to the organic ELdisplay device explained in the modification of Embodiment 2.

The organic EL display device may be a transmissive type. In case thatthe lower electrode is used as an anode electrode, it is preferable thatthe lower electrode is made of a conductive material whose value of awork function is large as well as whose light transmittance is high suchas ITO or IZO. On the other hand, in case that the lower electrode isused an a cathode electrode, it is preferable that the lower electrodeis made of a conductive material whose value of the work function issmall as well as whose light transmittance is high. Furthermore, in casethat the upper electrode is used as a cathode electrode, it ispreferable that the upper electrode is made of a conductive materialwhose value of the work function is small as well as whose lightreflectance is high. On the other hand, in case that the upper electrodeis used as an anode electrode, it is preferable that the upper electrodeis made of a conductive material whose value of the work function islarge as well as whose light reflectance is high.

Though the stacked structure is formed at each sub pixel in Embodiment1, it is possible that the stacked structure is formed at each regionprescribing the sub pixel with respect to red light-emitting sub pixelsemitting red and the green light-emitting sub pixels emitting green, andthe stacked structure emitting blue is formed at the whole surface ofthe display area with respect to blue light emitting sub pixels emittingblue. The upper electrode is formed over the stacked structure emittingblue so as to cover the whole surface of the stacked structure emittingblue. In this case, the red light-emitting sub pixel has a stacked stateof a stacked structure emitting red and a stacked structure emittingblue, however, the sub pixel emits red when electric current flowsbetween the lower electrode and the upper electrode. Similarly, thegreen light-emitting sub pixel has a stacked state of a stackedstructure emitting green and a stacked structure emitting blue, however,the sub pixel emits green when electric current flows between the lowerelectrode and the upper electrode. In the organic EL display devicehaving the above configuration, a connecting portion (connectingterminal portion or wiring for connection) for connecting the upperelectrode formed on the whole surface to the outside is formed on aninterlayer insulating layer at the periphery of the organic EL displaydevice. Even in such configuration, in order to suppress degeneration ofthe upper electrode by the insulating layer in the region in which theupper electrode is connected to the connecting portion, it is preferablethat the stacked structure emitting blue is interposed between the upperelectrode and the insulating layer. That is, the region in which theupper electrode is connected to the connecting portion has a stackedstate of the interlayer insulating layer, the insulating layer, thestacked structure emitting blue and the upper electrode. A part of theconnecting portion has a stacked state of the interlayer insulatinglayer, the connecting portion, the stacked structure emitting blue andthe upper electrode. The other portions in the connecting portion have astacked state of the interlayer insulating layer, the connecting portionand the upper electrode.

In the embodiments, the overlapping portion 23′ on a part of theinsulating layer 24 has a stacked state in which the auxiliary wiring25, the stacked structure 23, and the upper electrode 22 aresequentially stacked, however, in some cases, it may be alternatively astacked state in which the stacked structure 23, the auxiliary wiring 25and the upper electrode 22 are sequentially stacked from below on a partof the insulating layer 24 as shown in the schematic partialcross-sectional view in FIG. 12. The configuration and the structureshown in FIG. 12 can be applied to the organic EL display deviceexplained in the second embodiment or the modifications.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

1. An organic electroluminescence display device comprising: (a) a lowerelectrode; (b) an insulating layer having an opening, in which a lowerelectrode is exposed at a bottom of the opening; (c) an auxiliarywiring; (d) a stacked structure provided from a portion over the lowerelectrode exposed at the bottom of the opening to a portion of theinsulating layer surrounding the opening, including a light emittinglayer made of an organic light-emitting material; and (e) an upperelectrode; and (f) a protection film provided on the upper electrode andcapable of transmitting more than 80% of light generated in the stackedstructure, wherein a portion of the upper electrode positioned over theauxiliary wiring is electrically connected to the auxiliary wiringthrough a two-layer structure layer including a charge injection layerand a charge transport layer, and wherein the upper electrode covers thestacked structures and the two-layer structure layer forming theplurality of organic electroluminescence elements without touching theinsulating layer, and wherein the upper electrode partially contacts thestacked structure, partially contacts the auxiliary wiring, andpartially contacts the two-layer structure layer.
 2. The organicelectroluminescence display device according to claim 1, wherein thetwo-layer structure layer extends also between the stacked structurepositioned over the lower electrode and the upper electrode.
 3. Theorganic electroluminescence display device according to claim 1, whereinat least one layer of the stacked structure has a portion connected tothe auxiliary wiring.
 4. The organic electroluminescence display deviceaccording to claim 1, wherein voltage falling between the auxiliarywiring and the upper electrode is equal to or less than 5 V when thecurrent density of electric current flowing between the auxiliary wiringand the upper electrode is equal to or less than 10 A/cm².
 5. Theorganic electroluminescence display device according to claim 1, whereinthe upper electrode is made of a conductive material including magnesiumand the thickness of the upper electrode ranges from 4 nm to 20 nm. 6.The organic electroluminescence display device according to claim 1,wherein the protection film is made of a material selected from thegroup consisting of inorganic-amorphous insulating materials such asamorphous silicon (α-Si), amorphous silicon carbide (α-SiC), amorphoussilicon nitride (α-Si_(1-x)—N_(x)), amorphous silicon oxide(α-Si_(1-y)O_(y)), and amorphous carbon (α-C).
 7. The organicelectroluminescence display device according to claim 1, wherein theauxiliary wiring is made of a conductive material selected from thegroup consisting of aluminum, silver, nickel, copper, chromium,tungsten, niobium, tantalum, molybdenum, gold, titanium, cobalt,zirconium, iron, platinum, zinc, and alloys including the above metalelements.
 8. The organic electroluminescence display device according toclaim 1, wherein the lower electrode is made of a material selected fromthe group consisting of chromium, iron, cobalt, nickel, copper,tantalum, tungsten, platinum and gold.